Physical quantity detector

Abstract

A physical quantity detector includes a diaphragm including a displacement part that is displaced under external pressure, a ring-shaped fixing part that holds an outer circumferential part of the diaphragm, a holding member having a projection part that projects from an inner circumference of the fixing part toward a center at one surface side of the diaphragm, a support fixed to the projection part, and a pressure-sensitive device having a first base part fixed to the displacement part, a second base part fixed to the support, and a pressure-sensitive part provided between the base parts.

What is claimed is: 
     
         1 . A physical quantity detector comprising:
 a pressure receiving unit including a displacement part that is displaced under pressure;   a holding member including a fixing part that holds an outer circumferential part of the pressure receiving unit, and a projection part that projects from an inner circumference of the fixing part toward a center;   a support member fixed to the projection part; and   a pressure-sensitive device one end of which is fixed to the displacement part and the other end of which is fixed to the support member.   
     
     
         2 . The physical quantity detector according to  claim 1 , wherein the projection part is provided in an annular shape in the fixing part. 
     
     
         3 . The physical quantity detector according to  claim 1 , wherein
 the pressure-sensitive device includes a first base part fixed to the at least one part of the displacement part, a second base part fixed to the support member, and a pressure-sensitive part provided between the first base part and the second base part, the first base part and the second base part stood in line in a direction in which the displacement part is displaced, and   the first base part and the second base part are located in an direction to which the displacement part displaces.   
     
     
         4 . The physical quantity detector according to  claim 1 , wherein the support member includes:
 a column member stood in the projection part; and   a beam member connecting the column member and the second base part.   
     
     
         5 . The physical quantity detector according to  claim 4 , wherein the column member is provided within a region of the displacement part in the plan view from the direction in which the displacement part is displaced. 
     
     
         6 . The physical quantity detector according to  claim 1 , wherein a direction in which a part where the support member is fixed in the projection part and the first base part are arranged is orthogonal to the direction in which the displacement part is displaced. 
     
     
         7 . The physical quantity detector according to  claim 1 , further comprising a fixing member joined to the displacement part,
 wherein the first base part is fixed to the fixing member.   
     
     
         8 . The physical quantity detector according to  claim 4 , wherein the column member and the beam member are formed using different materials from each other. 
     
     
         9 . The physical quantity detector according to  claim 8 , wherein the pressure-sensitive device is formed using a piezoelectric material, and
 the column member is formed using a material having a coefficient of thermal expansion equal to or close to that of the piezoelectric material.   
     
     
         10 . The physical quantity detector according to  claim 8 , wherein the beam member is formed using a material having a coefficient of thermal expansion equal to or close to that of at least one of the holding member and the pressure receiving unit. 
     
     
         11 . The physical quantity detector according to  claim 10 , wherein the holding member is formed using a material having a coefficient of thermal expansion equal to or close to that of a constituent material of the pressure receiving unit. 
     
     
         12 . The physical quantity detector according to  claim 1 , wherein the pressure-sensitive device includes one or more vibration beams in the pressure-sensitive part. 
     
     
         13 . The physical quantity detector according to  claim 1 , wherein the pressure-sensitive device is a thickness-shear mode vibrator.